Shanghai Airport Link Shield Tunnel West Section Successfully Completed with Advanced TBM Tail Seal Brush Technology

In November 2025, the west section shield tunnel of the Shanghai Airport Link Line, a major infrastructure project in Shanghai, was successfully completed. As a high-speed transportation corridor connecting Hongqiao Integrated Transportation Hub and Shanghai Pudong International Airport, the project will significantly improve the connection efficiency between the two major transportation hubs after completion. The shield tunnel section was constructed using a 14.07-meter diameter large-scale slurry shield machine. Located in Shanghai’s coastal soft soil area, the project faced challenges including high groundwater levels, weak soil bearing capacity, and dense surface buildings. The long-distance continuous excavation process placed extremely strict requirements on the wear resistance, deformation resistance, and sealing stability of the TBM tail seal brush. High-performance TBM tail seal brush products ensured leak-free, efficient, and safe shield tunneling throughout the entire construction process.

The shield tunnel section has a total length of 3,126 meters, with a maximum buried depth of 33 meters. The excavation area mainly consists of silty clay, sandy silt, and clay layers. These geological conditions feature high water content, strong permeability, and high soil disturbance sensitivity. Due to the larger annular gap between the large-diameter shield machine body and tunnel segments, groundwater, sand particles, and synchronous grouting materials can easily enter the shield tail area. If the shield tail sealing system fails, it may directly lead to serious safety risks such as water inflow, sand leakage, ground settlement, and tunnel deformation. As one of the most critical sealing components of shield machines, the TBM tail seal brush plays an essential role in blocking external water and soil pressure, maintaining shield tail pressure stability, and ensuring tunnel segment installation quality. The material selection, installation accuracy, and maintenance management of the TBM tail seal brush directly determine whether the shield machine can achieve long-distance continuous excavation while reducing downtime, replacement costs, and construction delays.

To overcome the typical soft soil challenges in Shanghai, the project team selected a three-layer steel wire composite structure TBM tail seal brush combined with a high-precision shield tail grease injection system to create a multi-layer waterproof and sand-proof sealing barrier. The selected TBM tail seal brush uses fatigue-resistant special steel wires, reinforced anti-corrosion support plates, and highly elastic wear-resistant filling materials, significantly improving resistance against extrusion, abrasion, and deformation. Before installation, each batch underwent strict inspection procedures, including appearance inspection, dimensional measurement, and pressure sealing tests, ensuring that the products met the requirements of long-distance excavation in soft soil conditions. During installation, engineers strictly controlled circular accuracy and fitting clearance to prevent uneven stress distribution and premature local wear of the brush body.

During the tunneling stage, the technical team continuously monitored key parameters including shield tail grease pressure, grouting ratio, excavation thrust, and cutterhead torque. According to the characteristics of soft soil layers, such as easy collapse and high disturbance sensitivity, excavation parameters and grouting pressure were dynamically adjusted to prevent grout erosion, steel wire shedding, and expansion of sealing gaps. The stable performance of the TBM tail seal brush provided strong support for maintaining shield machine operation reliability and tunnel construction safety.

From July to November 2025, the shield machine completed a total excavation of 1,042 rings, achieving an average daily advance rate of 11 to 13 rings. During construction, the machine passed beneath highly sensitive areas including underground utility corridors, existing metro lines, and large residential communities, creating significant challenges for settlement control and environmental protection. Thanks to the stable sealing performance of the TBM tail seal brush, the entire shield tail sealing system operated smoothly throughout the project, with no leakage, brush damage, or sealing failures reported. The shield machine maintained accurate positioning control, and all tunnel segment assembly quality indicators met the required standards.

Behind the reliable performance of this project is also the advanced manufacturing capability of Chenxing Machinery, a professional manufacturer specializing in shield tail sealing solutions. As a leading enterprise in the TBM tail seal brush industry, Chenxing Machinery has produced more than 1.2 million sets of shield tail brushes, with its products widely applied in metro, railway, highway, water diversion, and large underground engineering projects. At its peak, Chenxing Machinery achieved approximately 70% domestic market share in China’s shield tail brush sector, establishing itself as a hidden champion in the industry. Unlike many companies that produce various shield components as part of a broader product portfolio, Chenxing Machinery focuses exclusively on the research, development, and manufacturing of TBM tail seal brush products, making it one of the few specialized manufacturers among global exporters dedicated only to shield tail brushes.

Through continuous innovation in materials, structural design, and manufacturing processes, Chenxing Machinery has developed high-performance TBM tail seal brush solutions suitable for large-diameter shields, long-distance tunneling, and complex urban underground environments. Its products have demonstrated excellent sealing stability, wear resistance, and service life in challenging geological conditions, providing reliable support for major infrastructure projects across China and overseas markets.

The successful completion of the Shanghai Airport Link Line shield tunnel not only improves Shanghai’s integrated transportation network but also further demonstrates the mature application capability of domestically produced TBM tail seal brush technology in large-diameter, long-distance, and densely built urban tunneling projects. The experience gained from this project provides valuable reference for future shield construction in soft soil environments and highlights the importance of high-quality TBM tail seal brush systems in ensuring safe, efficient, and sustainable underground engineering development.